Radio frequency distribution system



RADIO FREQUENCY DISTRIBUTION SYSTEM J. WEINBERGER 2,003,962

Filed March 29, 1929 3 Sheets-Sheet 2 INVENTOR JULIUS VIEMIERGER ATTORNEY Exan'nnsa' txarmner June 4, 1935. J. WEINBERGER' more FREQUENCY mswamu'rrou SYSTEI Filed larch 29,' 1929 3 Sheets-Sheet 3 INVENTOR JULIUS new man ATTORNEY UNITED STATES mammal PATENT OFFICE RADIO FREQUENCY DISTRIBUTION SYSTEM Julius Weinberger, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application March 29, 1929, Serial No. 350,869

14 Claim.

This invention relates to a radio frequency distribution system especially adapted for apartment houses, hotels and the like, and more particularly it relates to a system wherein energy collected on a single antenna may be efficiently distributed to a plurality of translating devices or receivers located within separate apartments, or, as I shall term them hereinafter, acoustically isolated points.

Heretofore each lessee of an apartment finding that he could not get good reception with his receiver on an indoor loop or a similar indoor antenna because the shielding effect of the building was too great, erected a separate antenna for his individual receiver. This resulted in a large number of crude looking antenna: which were objectionable both to the lessor as well as to others viewing the building upon which the antennae were placed. Accordingly, one object of my invention is to provide a radio frequency distribution system wherein a single collector of electromagnetic energy may be utilized to energize a plurality of receivers.

However, if a plurality of receivers are coupled in an ordinary fashion to a single antenna, it has been found that the receivers interact, causing annoying disturbances or loss of eficiency in reception. It may also be found that with such ordinary coupling certain frequencies are received with much more efiiciency than others. Hence, another object of this invention is to provide a radio frequency distribution system wherein radio frequency energy collected by means of a single collector may be distributed without frequency discrimination to a plurality of receivers and wherein the receivers will not interact with each other.

In another aspect, my invention also includes and has for another object the provision of a method for efficiently distributing radio frequency energy from a single collector to a plurality of translating devices and this method includes collecting the energy at a single point, and transmitting the energy, with or without amplification, without substantial frequency discrimination to a plurality of acoustically isolated points.

Other objects as well as advantages of my invention will be apparent as the description thereof proceeds; and, my invention will be best understood as to its mode of operation and possible ways of carrying it out by referring to this specification together with the accompanying drawings in which Figure 1 is a wiringdiagram showing an installation of my improved radio frequency distri-- bution system in an apartment house;

Figure 2 is a more detailed wiring diagram of an antenna and one of its associated loaded two wire transmission lines; 5

Figure 3 is a wiring diagram similar to Figure 2 showing the use of a transposed two wire aperiodic or loaded transmission line, and

Figure 4 is a detailed wiring diagram of another distribution system. 10

Referring to Figure l, I have diagrammatically shown therein an apartment house in cross section and in elevation. Suitably mounted on the roof of the building is a central antenna or energy collecting device I. The collector I supplies radio 5 frequency energy to a plurality of translating devices or receivers 3, located in different apartments or, as I chose to call them acoustically isolated points. Each translating device is coupled to one of a plurality of two wire aperiodic 20 transmission lines 5. Each line 5 is coupled to the antenna through a separate amplifier 'l which 5 may include one or more stages of ampliflcationi A central volume control unit 9 is provided for controlling the input to each of the amplifiers 1. 25 There is also provided a central energy source II for supplying energy to the amplifiers 1. The volume control unit 9, energy supply I l, amplifiers I together with a lightning arrester l3 and ground connection l5, are preferably located, as shown, in the pent house of the building or at some other centrally located point at a relatively high elevag tion above the earths surface.

In order to provide for distribution of energy without frequency discrimination to each apartment, the transmission lines 5 should be made aperiodic and this is preferably done by loading them. To further insure an aperiodic condition of the transmission lines they should be terminated by impedances I! which are preferably 40 resistances having a value equivalent to the ohmic surge impedance of one of the transmission lines and hereinafter referred to as terminating impedances.

In order to insure a sufiicient volume of energy in each apartment the receivers 3 may be coupled to the lines 5 through amplifiers IQ of one or more stages and which may be energized from the central supply ll. Outlets or contacts 2| should also be provided in each apartment for easy connection to one of the two wire lines 5.

In connecting a receiver to the line it will only be necessary to bring connections from the ground and antenna terminals of the receiver to the outlet 2|.

The volume control unit 9 is better illustrated in Figure 2 and it comprises a resistance 23 in the antenna lead-in from which a variable tap 25 for the coupling tube 21 may be taken. The coupling tube 21 indicates one of the amplifiers in Figure 1 and the numerals 29, 3| indicate the manner in which connections are taken from the resistance 23 to other coupling tube units or amplifiers 1. As already indicated, a plurality of tubes 21 may be cascaded in any suitable fashion to supply one of the lines 5.

In Figure 2 the central energy supply unit has been illustrated to be batteries, but it is to be understood that this is only by way of example and the coupling tubes may and preferably are as shown in Figure 3 of the alternating current type. In the latter figure a volt line is shown supplying a rectifier 33 for supplying the anode potential for amplifier tube 21, and a transformer 35 is shown for energizing the cathode of the coupling tube located in close proximity to the antenna. Also, in Figure 3 numerals 29, 3| indicate the manner in which additional amplifying coupling tubes or electron discharge devices may be coupled to the antenna l.

Turning back to Figure 2 the output of electron discharge device 21 is fed by transformer connection into one of the transmission lines 5. The transmission line is loaded by inductances 31 and is terminated by a resistance 39, corresponding to the aforementioned terminating impedance I1, and having a value equal to the surge impedance of line 5. By so loading the line and terminating it the line is made aperiodic, that is, it is made to transfer all frequencies within a designated range, (for example, the broadcast range) with substantially equal efficiency, or in other words, without transferring energy of a certain band of frequencies to a greater degree than energy of other frequencies.

Each receiver 3 is coupled to aperiodic line 5 through an amplifier |9 which, as exemplified in Figure 2 comprises an electron discharge device 4| whose output is fed through a transformer 43 into receiver 3. A resistance 45 may be provided across the short branches 41 by which tube 4| is coupled to line 5, to which the input terminals of tube 4| may be connected. Resistances 45 also tend to prevent reactive loads, as when tuning the receivers, from being applied to the two wire lines, and thus tend to preserve their aperiodicity at all times.

By the use of an aperiodic line 5 and terminating resistances 39 it has been found that interaction between the receivers is eliminated and this elimination is also assisted by the use of coupling tubes 4| which, when there is a tendency for feedback to occur between the receivers on the same line and between the receivers of different transmission lines, introduce large impedances into the feedback paths.

To further improve reception the line 5 may be transposed or crossed as shown in Figure 3 in order to reduce pick up from power lines used for lighting purposes or the like. In addition, to improve reception especially on receivers utilizing a tuned input circuit ahead of the first radio frequency amplifier tube, there may be added in the short branches 4! a dummy antenna comprising an inductance 49 and a condenser 5|. By the term dummy antenna circuit is meant a series resonant coupling device disposed between the aperiodic transmission line 5 and the receiver input. They are inserted to provide the necessary circuit elements to work in with radio receivers having means for tuning antenna circuits. In general, there are two classes of receivers. One of these classes uses an aperiodic antenna, and has no means for tuning its antenna circuit, the other class employs tuning devices in the antenna circuit. A receiver of the first class can be connected directly to the transmission line or to the coupling tube output, but a receiver of the second class will not operate efficiently unless coupled to the transmission line through an artificial, or dummy, antenna circuit. In general, therefore, to suit all types of receivers, it is desirable to include a dummy antenna in the individual outlets.

Of course, other types of antennae other than that shown in Figure 1 may be utilized to good advantage. Thus in Figure 4 I have illustrated by numeral 53 a T type of antenna the down leads 55 at each end of which are connected to ground through a condenser 51 and a filter device 59. The filter 59 passes those frequencies included Within the ordinary broadcasting range.

Coupling from the filters 59 to transmission lines 6| is effected through transformers 63 which may have any suitable ratio for its primary and secondary windings. The line 6| is made aperiodic and may be, as already described, transposed. Receivers 65 may be coupled to the line or to branches 6! in the manner shovm or in any other suitable way. The line and branches should, of course, be terminated by suitable resistances H, 13, each terminating resistance having an impedance equivalent to the surge impedance of the line across which it is connected. Amplifiers may or may not be, as is found advisable, interposed between the filters 59 and lines 6| and between receivers 65 and the transmission lines 6i and branches 61. Resistances 15 may be employed to good advantage for coupling the receivers to the lines and if desired, the receivers may be coupled to the line as shown in Figure 3 through dummy antenna comprising condensers 5| and inductance coils 49. The center of the T antenna 53 may be grounded through the coil 11.

It is to be noted that in Figure 4 energy collected by collector 53 is directly transferred aperiodically to each of the receivers. This aperiodic transfer, or transfer along a line having filter characteristics, prevents interaction between the receivers.

It may also be found, with reference to the scheme disclosed in Figure 4 and in fact with reference to the systems shown in Figures 1, 2 and 3, that a single antenna may not collect sufficient energy to supply a very large number of receivers, even after amplification of the collected energy a practical number of times before the energy is fed to the receivers. In such a case a plurality of my systems may be used to good advantage and yet, because the relative number of antennae will be small, as compared to the case where each receiver is provided with a separate antenna, they will not present an undesirable appearance.

It is obvious, of course, that the central supply source such as shown for example in Figure 1, at H, may be utilized for supplying the amplifiers located at the differently acoustically isolated points. Suitable switches may, of course, be provided as will be apparent to one skilled in the art, so that any point may be de-energized at the will of, for example, the lessor.

While I have shown several preferred forms of my invention, it is to be understood that I am not to be limited thereby, but solely by the scope of the appended claims. J

What I claim is:

. 1. In a system for distributing radio frequency energy, an antenna for collecting radio frequency energy, means at the antenna for amplifying the energy so collected, means comprising a two wire loaded transmission line for transferring aperiodically the amplified energy to isolated points, and means at each one of said isolated points for feeding the transferred energy into a translating device. 1 1

2. In a radio frequency distribution system an antenna, a plurality of electron discharge devices coupled thereto, a two wire loaded transmission line coupled to the output circuit of each one of said electron discharge devices, and a plurality of translating devices coupled to each loaded transmission line.

3. In a radio frequency distribution system an antenna, an electron discharge'device coupled thereto, a loaded two wire transmission line coupled to the output circuit of said electron dis charge device, a terminating resistance of a value equivalent to the surge impedance of said line connected across the remote end of said line, and a radio receiver coupled to said line at a point remote from said antenna.

4. A radio frequency distribution system comprising an antenna, a plurality of electron discharge devices coupled thereto, a transmission line coupled to the output circuit of each of said electron discharge devices, loading coils in each one of said transmission lines for the purpose of improving its transmission characteristics and for reducing the attenuation of radio frequency currents, a resistance terminating each of said lines, electron discharge devices coupled to each of said lines at a plurality of acoustically isolated points, and means for coupling the output circuit of each of said last mentioned electron discharge devices to a translating device located at each of said acoustically isolated points.

5. In a system for the distribution of radio frequency energy, an aperiodic grounded energy collecting means including a resistance, a plurality of amplifier devices coupled to said collecting means across said resistance, a plurality of loaded two-wire aperiodic transmission lines each one thereof being coupled to the output of one of said amplifier devices, a plurality of sets of remotely situated translating devices each device of each set being coupled to one of said transmission lines through a resistance and series resonant circuit.

6. In a system for the distribution of radio frequency energy, an aperiodic grounded energy collecting means including a resistance, a plurality of amplifier devices coupled to said collecting means across said resistance, a plurality of loaded two-wire aperiodic transmission lines transposed at predetermined intervals, each thereof coupled to the output of one of said amplifier devices, a plurality of sets of remotely situated translating devices each device of each set being coupled to one of said transmission lines through a resistance in series with a series resonant circuit.

7. In a radio frequency distribution system, an aperiodic antenna, at least one coupling tube having an aperiodic input circuit ad-Justably coupled thereto, a pair of conductors inductively coupled to the output circuit of said coupling tube, a plurality of spaced radio receivers connected to said conductors, and a coupling means including a resistance in series with a condenser between said conductors and the input of each receiver and a plurality of similar loading coils inserted in said conductors between said several coupling means whereby said conductors transmit a broad band of radio frequency currents to each of said receivers.

' 8. A multiplex high frequency receiving system for operating a plurality of receivers from the same energy pick-up device, comprising, in combination, means for picking up high frequency energy to be received, a transmission line associated with said pick-up means, said line being loaded at predetermined points to pass energy of frequencies up to the highest desired fre-- quency, and a plurality of receivers coupled to said line at points electrically intermediate to said loaded points.

9. A multiplex high frequency receiving system for operating a plurality of receiving devices from the same energy pick-up device, comprising, in combination, means for picking up high frequency energy to be received, a line conductor associated with said pick-up and leading to said receiving devices, said receiving devices being connected through an impedance to said line conductor at intervals, and loading coils interposed in said conductor intermediate said receiving devices, the structure of said system being such that said line conductor has an electrically infinite effective length, and the constants of said loading coils having a value such that said line exhibits the characteristics of a uniform attenuation line passing currents of a frequency as high as the highest frequency desired to be received.

10. A multiplex high frequency receiving system for operating a plurality of receiving devices from the same energy pick-up device, comprising, in combination, means for picking up high frequency energy to be received, a line conductor associated with said pick-up for transmitting energy to all of said receiving devices, said receiving devices being connected to said conductor at intervals through coupling impedances, and loading coils interposed in said conductor be tween said receiving devices.

11. A method of operating a multiplicity of high frequency receivers, each comprising a signal responsive device, from the same energy collecting system, which comprises collecting high frequency energy to be received, transmitting with substantially uniform attenuation over a path the portion of said collected energy lying within the spectrum of frequencies to be received, and withdrawing at electrically separated points of said path portions, independently selectable as to frequency, of the said collected energy traversing said path, and supplying said withdrawn portions to said signal responsive devices.

12. A method of operating a multiplicity of high frequency receivers, each comprising a signal responsive device, from the same energy collecting system, which comprises collecting high frequency signal energy to be received, transmittin with substantially uniform attenuation over a path the portion of said collected energy lying within the spectrum of frequencies to be received, maintaining the signal energy transmitted over said path free of extraneous influences, and withdrawing at electrically separated points of said path portions, independently selectable as to frequency, of the said collected energy traversing said path, and supplying said withdrawn portions to said signal responsive devices.

13. A multiplex high frequency receiving system for operating a plurality of receivers from the same energy pick-up device, comprising, in combination, means for picking up high frequency signal energy to be received, a transmission line associated with said pick-up means, said line being so constructed and arranged that said signal energy is transmitted over it free of extraneous influences, said line being loaded at predetermined points to act as a uniform attenuation line passing energy of frequencies up to the highest desired frequency, and a plurality of receivers coupled to said line at points electrically intermediate to said loaded points.

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